1. Field
The present application relates to a non-linear microscopy and a non-linear observation method.
2. Description of the Related Art
In recent years, a momentum of biotechnology industry is skyrocketing, and in particular, a demand for three-dimensional resolution microscopy in which a biological sample is set as an observational object, is increasing more and more. In the three-dimensional resolution microscopy, a confocal microscopy with high spatial resolution has been widely used from old times to present time. A conventional confocal microscopy observes a fluorescence generated, by a fluorescence molecule contained in a biological sample, in a linear intensity with respect to an intensity of irradiating light (a signal obtained through a linear optical process), and in recent years, a non-linear microscopy that observes a light generated, by a specific kind of molecule contained in a biological sample, in a non-linear intensity with respect to an intensity of irradiating light (a signal obtained through a non-linear optical process), has been drawing an attention.
The non-linear microscopy uses a light with relatively long wavelength (near-infrared ray, for example) as the irradiating light, so that the sample can be observed up to a deep portion thereof. Further, since the aforementioned non-linear process takes place only in a minute region in the vicinity of a focus of an objective lens, an image obtained by the non-linear microscopy becomes an image of an extremely thin layer (sectioning image). As one of such non-linear microscopy, there is a CARS microscopy that utilizes a coherent anti-Stokes Raman scattering (CARS) as the non-linear process (refer to Japanese Unexamined Patent Application Publication No. 2009-47435 and the like).
However, the conventional CARS microscopy has a problem that a resolution in an optical axis direction (z direction) is lower than a resolution in an inplane direction (xy direction) perpendicular to the optical axis.
Accordingly, the present application has a proposition to provide a non-linear microscopy and a non-linear observation method capable of increasing a resolution in an optical axis direction.